Process for the treatment of matte to recover metallic salts



Sept. 2, 1952 M. J. UDY 2,609,272

PROCESS FOR THE TREATMENT OF MATTE TO RECOVER METALLIC SAL/ TS Filed Dec. 9, 1946 SULPHIDE ORE OR CONCENTRATES CONTAINING IRON SULPHIDE,COPPER SULPHIDE AND ZINC SULPHIDE ROAST TO CONVERT ABOUT SULPHUR ONE-THIRD OF THE SULPHUR DIOXIDE OF THE SULPHIDE CONTENT TO SULPHUR DIOXIDE 'TO ANY E FUSE OR SMELT ROAsTED PRODUCT SULPHIDE MATTEi COOL SOLIDIFY TO WASTE I AND ORANULATE I I FINELY DIVIDED. MATTEJ HYDROGEN REACTION TANKS ARRANGED SULPHURIC ACID SULPHIDE FOR COUNTER-CURRENT FLOW I SOLUTION SOLID PRODUCT CONTAINING FERROUS SULPHATE SULPHIDES OF COPPER AND ZINC SOLUTION SOLID ZINC SULPHATE TO MARKET OR ELEOTROLYsIs I 0R DECOM OSITION TO PRO- LEACH WITH WATER AND FORM AN ACID SOLUTION OF ZINC DUCE OX'DE AND COPPER SULPHATES EZ EEE C ACID SOLUTION OF ZINC PRECIOUS AND COPPER SULPHATES METALS ROAST UNDER OXIDIZING CONDITIONS IN PRESENCE OF SULPHURIC ACID I {TREAT wITH HYDROGEN suLPHIIg. INVENTOR MARVIN J. uDY BY L-Ific SULPHATE SOLUTIO YOOPPER SULPHIDEJ m q Patented gepi. 2, 195 2 PROCESS FOR THE TREATMENT OF MATTE To RECOVER METALLIo- SALTS l 7 Marvin J.- Udy, Niagara Falls, N.- Y., assignor to 4 Guaranty Investment Corporation, Limited, Montreal, Quebec, Canada, a corporation of Canada Application December 9, 1946, Serial No. 715,112

"This invention relates to metallurgy and has for-an object the provision of an improved metal-v lurgical method or process. More particularly the invention contemplates the provision of an improved zinc recovery method or process. A specific object of the invention isto provide an improved method or prooessfor separating from the iron contained in iron sulphide-bearing material other elements contained in the iron sulphidebearing material, particularly zinc, with the pro.- duction of (1) an aqueous solution containing the iron of the iron sulphide-bearing material and substantially free of other elements contained in the material, (2). gaseous hydrogen sulphide containing sulphur originally combined with iron in the iron sulphide-bearing material and (3) one or more solid products containing substantially :all other elements contained in the iron sulphide- ;bearing material and from which the other elements such as zinc may be recovered readily.

-Throughout. the specification and claims, the :term'. ore is intended to, include other iron. sulphide-bearing materials such as concentrates aslwellas crude ore. r v

Thepresent invention is based in part on my discoverythat the other elements contained in ironsulphide-bearing material may be separated effectively, from :iron,contained l in the iron sulphide-bearing material by treatment of the mate'rialwith a mineral acid. Thus, for example,

-I hav.e;f.ound thatamatte product containing sulphur, iiron,: copper, nickel, cobalt, zinc and such other elementsas arsenic, antimony, tin, molybdenum, selenium, tellurium, vanadium and precious metals can be digested with an aqueous solution of sulphuric acid to produce (1) an aqueous solution of ferrous sulphate substantially free-lot. all other elements contained inthe iron sulphideebearing material and containing a large proportion or substantially all of the iron of the iron, sulphide-bearing material, (2) gaseous hydrogen sulphide containing sulphur combined with iron in the iron sulphide-bearing material and ('3) a solid product containing substantially allof the balance of the sulphur of the iron sulphidebearing material and substantially all other elements contained in the iron sulphide bearing material. The invention may be employed advantageously in the treatment'of. iron sulphide-bearing materials containing the elements, zinc and copper to form solid products containing one or more of those elements in concentrated forms and largely free of iron.

,1; have found, also, that a solution of ferrous sulphate; free of zinc can be obtained by treating 4 Claims. (Cl. 23-125) matteicontaining iron and zinc sulphides with an aqueous solution of a mineraliacid if contact of; the matte with the aqueous solution is maintained and reaction continued until thesolution becomes neutral or substantially neutral. Zinc of thezinc; sulphide may be obtained in a solid residue in the form of zinc sulphide or the zinc may be obtained as, zinc sulphate or ,aspzinc sulphide and; zinc:

sulphate.

According to the present invention, ore con: 1 taming iron sulphide and a sulphide of zinc' o1} sulphides of zinc and copper is smelted with suitable fluxing material to produce a matte Containing sulphides of iron and zinc which is soluble .in a mineral acid such as sulphuric acid and a separable slag containingthe gangue materials oi V the-ore. Ihe matte-and slag products :are separated, and the matte subsequently is digested with acid to effect the separation of iron from other metals contained therein. Treatment of the matte with an aqueous solution of an acid such as sulphuric acid results in the production of gaseous hydrogen sulphide, an aqueous solution of ferrous sulphate containing a large proportionpi substantially all of the iron of the matte and a solid product comprising one or more sulphides of the metals copper and zinc, together with any; precious metals which may be present inthe ore-.

Zinc present in the matte may be converted o s as o. ro ma e in w h h r m i qn of sulphur to metal does not exceed one atomof sulphur for each atom of metal. For example pyritic ore containing'iron pyrite (FeSz) and sulphide preferably is ,smelted under conditions such that the amount and proportion of sulphur inthe 7 resulting matte does not exceed one atom:

of sulphur for each atom of iron (Fe zinc (Znl;

and any other metallic element containedthere Thelsmelting of a pyritic ore preferably is so con: ducted that the matte product formed contains a:

tions of sulphur may be carried out in any suit-l.

able manner, as, for example, (1) by smelting the ore under oxidizing conditions to oxidizeexcess] sulphur, (2) by smelting a charge comprising the ore, iron oxide and a reducing agent suchasfcokej t e roc s o s l l n s l ha l l s ma be wasted orv disposed of in any suitable manner In practicing the invention, iron sulphidebear-. ing ore preferably is smelted under such condi-;

to reduce the iron oxide to metallic iron and effect chemical combination of the metallic iron with the excess sulphur, or (3) by smelting a charge of the ore in the presence of sufiicient metallic iron to combine with the excess sulphur. Smelting of thegore maybe carried out under conditions such as to produce a matte product containing free or elemental iron. The production or incorporation of free iron in the final matte product insures the establishment of the proper ratio of able amount of metallic iron may be incorporated in the final matte product. Usually, an amount of metallic iron equal to a fraction of onepercent of the weight of the matte insures proper solubility of the matte product.

The matte may be subjected to the action of acid in any suitable physical condition and according to any suitableprocedure. Preferably, the molten matte produced by smelting sulphide oreis'cooled and solidified, and the solidified matte is ground to form a finely divided .matte product- The matte may be ground to form a product co'mprising'particles of any suitable size. The time required for completion of the reaction between the'acid and the matte depends to some extent upon the sizes of the matte particles, the reaction-taking place more rapidly when smaller particles of matte are employed. Generally, reaction between the matte and acid proceeds rapidly to completion when a matte product consistin'g largely of particles small enough to pass a lllq-mesh screen is employed.

Treatment ofthe matte with acid may be carried-out according to any suitable procedure as, for example, in 'a batch-type operation or in a counter-current type operation, and an aqueous solution of acid of any suitable initial concentration or strength may be employed. Usually, I prefer to employ; an aqueous solution of sulphuric acid containing sulphuricacid in such concentration that treatment of the matte with the acid resultsin -consumption of all of the acid of the solutionandthe production of a neutral or substantially neutral solution of ferroussulphate, but l-"may employan aqueoussolution of sulphuric acid containing sulphuric acid in such concentraman that trea'tmentof the matte results in consumpti n-of-only aportion of the acid of the solutidn and the production of an aqueous solution of ferrous'sulphatecontaining a small amount of free '-ac'id.- -Inthe treatment of zinc-bearing matte" products, acid should *be employed in amounts suchthat the solutions of ferrous sulpirate produced contain not more than about 15 grains of'sulphuric acidper liter of water conmines-m the solutions.

=In-treating matte with an aqueous solution of sulphuric acid,-I prefer to employ a solution of such cencent'ration and. to so conduct the acid -l sulphur to metal in the matte product. Anysuitiron and zinc, it is advisable to employ tem era tures below the boiling temperatures of the liquids in order to maintain the liquids saturated with respect to hydrogen sulphide. Boiling results in driving off the hydrogen sulphide rapidly, and, consequently, zinc may be converted to a-soluble state. In the treatment of zinc-free-matte products such, for example, as matte products con- .taining sulphides of iron and copper, boiling temperatures may be employed. The maximum strength of concentration of the acid solution employed will 'be determined to some extent by the permissible temperature of treatment, since the-concentration of the ferrous sulphate solution produced depends upon the strength or concentration of the acid solution employed and the temperature of treatment.

In the treatment of zinc-bearing matte products-I prefer to conduct the acid treatments at temperatures between about 50 C. and the boiling temperatures of the liquids :and to employ acid solutions of such concentrations as to produce concentrated ferrous sulphate solutions from which ferrous sulphate can be crystallized upon cooling to temperatures between the temperature of treatment and about 25 C. I may, however, employ relatively weak acid solutions andproduce neutral or substantially neutral solutions 'of ,ferrous sulphaterfrom whichferrous sulphate will not crystallize uponcooling toa temperatureof 25C. or lower. I prefer to treat zinc-bearing matte with-acid in a counter-current system, employing a series of tanks or vats, introducing untreated matteinto the firsttanl; or vat or other receptacle ofithe series while introducing the initial aQUEOLlSaSOllP.

tion of sulphuric acidinto the last vat or tank of the series, effecting partial decomposition :of the matte and partial consumptionof the acid in each tank,- passing residual'solid material. to each of the various vats'or tanks invseries from'the first to the'last and passing the acid solution to each of the vats or tanks in series from thezlast to the first, withdrawing from the first. vat or tank a substantially neutral concentrated solution of ferrous sulphate and withdrawing from the .last tank or vat a substantially iron-free sulphidea bearing "product or a sulphide-bearing lproduct relativelylow in iron. I- prefer to heat the liquid in the'last-tanko'r vat to a temperatureo'f about 70 Churhigher. Heat developed'asthe result of the reactions maintains the temperatureof the liquid in the first tank at about '50 C.

The solid sulphide-bearing product obtained from' the last tank or vat in the series maycontain zinc sulphide and other metals such aslcopper, nickel, cobalt, silver, gold and platinum which maybe-present in the mattelsubjected-to the acid treatment originally. Separation-and recovery of the various metals which may bepresent in the sulphide-bearing product may. be carried out iii-any suitable manner.

In treating zinc-bearing matte in 'a :countercurrent system inaccordance with the invention,

51?- gold and platinum. willlbe recovered in the last tank or vat.

- the treatment as irbi ifsulpliidebearina are containing g'zm'c and clip er," the finalf's'olid'f residue resulting from"anacidtreatnient or a matte obtained Tsmelting'fthe ore mayicoiis'ist oisulphides of zinc and copper. The sine and copper oi'suchaproduct may. be. separated -,(1) by the c'opperby'treatmentvof the solutioniwith hy-.:

drogen sulphide; Hydrogen'sulphide produced in the acid digestion treatment of the matte preferably is employed for precipitating copper;

Copper sulphide is separated from the zinc sulphate solution by .decantation or filtration, and

the zinc sulphatesolution may be returned, in; whole or in part, to the system in the acid'treat-' Themethod or process of the invention may be employed with" advantage "'in thetrea'tm'ent of;

iron sulphide=bearingmaterials'of all grades. It' may" be "employed with particular advantage in the treatment of iron sulphideebearing sores or other materials; containing "relatively small, amounts of copper. in addition to zinc. Prac-r. tically quantitative separation and recovery may:

be accomplished intreating ores containingtas little as about'two-tenths of one percent;(0.2%)

or less of a metal such, for example, as, copper, nickel, cobalt and zinc. Ferrous sulphate and hydrogen sulphide are produced'as substantially pure lay-products.

The process of the inventionmay be employed; advantageously to-produce valuable compounds of metals such as copper and zinc which are marketable as such or which may be employed in the production of those metals in elemental forms. Thus, for example,acopperfree solution of zinc sulphate produced in the process may be subjected to electrolysis to-produce metallic zinc orevaporated to dryness to produce solid zinc sulphate which may be marketed as such or subjected to a decomposition treatment 'atan elevated temperature to produce solid zinc oxide for m r etin er or-su sequentr du tion in m t llic zinc. Copper sulphide produced in accordance with the invention may be subjected to an oxidizing treatment withair or other oxygen-contain ing gas at an elevated temperature to produce copper oxide ,or with air or other oxygen con-, taining gas in the presence of sulphuric acid at an elevated temperature to produce copper vsul+ phate. The copper oxide and the copper ,sulphate may be recovered and marketed as such or they may be utilized as sources of copper in, electrolytic processes. Copper oxide and copper sulphate are desirable sources of copper for elec-, trolytic processes, and copper oxidemay be reduced, directly to metallic copper icy-means of carbonaceousor non-carbonaceous reducing ma,-, terials. r p g In theseparation of zinc and copperv bytreat: mentof an aqueous solution of the sulphates with hydrogen sulphide, a solution having an, acid;

reaction-meme empl yed advanta s y to pre- 6? vent precipitation iof-z'inc sulphide. An acid solution: may be produced by employing an acid aquousliquldlinformingthesolution. if The productionand acidetreatmentof matte inr 1 accordance with vthe invention are illustrated by:

the following examples; I

Ore of the following analysis with respect ta nickel, copper, iron and sulphur was smelted with limestone, iron 4 oxide ,7 and coke --to produce slag? and a-matte product of theanalysis indicatedbe f low with respect tonickel, copper, iron-and sul"- phurg 5 r M: 7,.

., O e m fi A quantity of matte of theflabove-indicatedj composition, weighing three'hundred fifty pounds (350 lb.) and containing 5' e was ground to form-a'finely divided product conperiod of about eightyminutes' (BOmintfi Treatment of the matte productfwith the'su pliuri'c'aci-d solution resulted 'in the-production} of a" solution and a residual matte productofthe following compositions:

v Solution", 1 Weight pouncls 3 SD. g! Fe pounds 1- 1;; FeSO4 do 582 Ni '.L Nil Cu s Nil-1 Weight Ore of the following analysis with respect to copper, iron and sulphur was smelted with limestonefiron oxide and coke, to produce slag and" a matte product'of 'the analysis indicated below with respect to'iron, sulphur and copper:

-- Ore analysis Per cent anaemia Mattmanalysisr .i

:1 a Pencent: Fe t 63:00; r i I v 3030 A quantity of matte of the 'above indica'ted composition, weighing -'-seven hundred seventyfive pounds (-7'7 5 1b and containing was ground to form a finely divided product consisting largely of'particle'ssmall enough to wrest: IOO-mesh screen, and the finely divided. nro'ducvwas treated in 'asingle digestion tank. an" "aqueous solution of sulphuric acid; formed by mixingone thousand two hundred siikty pounds '(13260' 1b.)" of sulphuric acid (Hz-S04, sp. gr. 1'.84)ww'rthkfivei thousand four hundredlpounds (5,400 lb.) of water (H2O), at

a: maximum. temperature, vof 150 E. during a; period of about one andone-half hours.

\ Treatment. of the. matte product withsulphurici acid solution. resulted in the. production of a2, solution and a residual matte product of the bllbw 'fl oi pdsit jns;

Solution: weight'fincluding wash water) pounds 7,950.- spi gr 1122s L pounds 48D ou v,. Nu

Residual-V matte Analysis .of matte l Peri-cent Zn: 4.18" Cu 3.25 Fe- 60.20 S -4 32.37- 60 Therproduct of the. digestion treatment was:v filtered, the, residue was. washedewith water i and; aiwfiltrate. and a .sulphideebearing residue'aof ithe following compositions; were; obtained A quantity of zinc-bearing matte ofth'je lowing-v compositionfwas' ground to form 'a finely divided product consisting largely 'of particles small enough" to passza IOU-mesh screen, and

the-f finely" divided product -was digested in a;

counter cu'rrent system with an aqueous solution f of sulphuric acid "with the"; produotiolr of af neutral f solution 10f ferrous sulphate: I -Andlysis of1fiatt; A

intermediate 1 the: first and': lasti'dige'stion recep;.- tacles T to: precip'itatei or crystallize? zincv sulphat formed :in itheidigestion vtreat'nient.

Ai-substantially neutral ferrous sulphate solu tion freevofrcopper':and' zinc:was withdrawn'fromthe? first receptacle.

: A sulphide residue of the following coniposition and beneficiatedi with respect toizin'c was withdrawn from: the last receptacle;

The": sulphide residue contained 42-72% or the zlncbf the origin -matte and 57 8%' ofithe' zinc of theori'ginal matte was recovered intli'e form offzinc sulphate- A preferred process of the} invention is'fillus trated in thesiaccompanying flow sheet."

-I claimz v v 1. The 'methodpf 'recOVeri-ngzincfrom matte containing sulphides of iron 'and zincwhich-com prises digesting the matte in finely divlded form with an aqueous solution of "sulphuric acidin 'a counter current' system comprising a series of receptacles, the sulphuric'a'cid being of suchcon-- centration as to produce a sub'stantially neutral solution of 'ferrous sulphate Whenreaotd with the iron sulphide oftheamatte by mandating untreated matte into the first rece'ptacl'e of- 'theseries and'introducing the solutionoff 5 sulphuric acid'initially into the last receptacle of the series, effecting partial decomposition of the matt'eand partial consumption of the acid solution 'in *e'ach receptacle, withdrawing the sub'stantially neutral solution of ferrous sulphate from the first" re-" ceptacle; continuing the digestion treatment by passing residual 'solid material "toeach of the various receptacles in series from the first to 'th'e last and passing the-acid solution to" eaeh ofthe' receptacles in 'series from' the last to the era; coolingthe acid solution at apoint intermediate the 'last"and'.first receptacles :to crystallize'and recover a. portion of the zincpf-thematteas zinc sulphate, withdrawing ir0m the 'last' re ceptaclea solid-residue containing the're'mainder of the -zinc of the matte in the form of 'zinc su 1-' phide and treating theisolid residue to recover a zinc product therefrom.

2; The": method of recovering :zincirom mattecontaining sulphides of iron"and zinc"w lii 'ch comprises digesting the matte with an aqueous solutionfof 'sulphuricaci'd in such an amount that there is produced a concentrated; substantially neutral solution" of fer'rous sulfate substantially" free or all elements other than iron 'originally present in the matte, gaseous hydrogen sulphide containing sulfur originally combined with iron in the matte, and a solid residue containing all of the zinc and a portion of the iron originally present in the matte, withdrawing the solution of ferrous sulfate, passing the residual solid material into contact with an aqueous solution of sulfuric acid in such amount that there is produced an acid solution containing the remaining iron of the matte as ferrous sulfate and a portion of the zinc of the matte as zinc sulfate, and a residue containing the remainder of the zinc as zinc sulfide, withdrawing the acid solution and cooling it to crystallize zinc sulfate, employing the acid mother liquor as the aqueous sulfuric acid solution in the first mentioned digestion step, and treating the zinc sulphide-containing residue to recover a zinc product therefrom.

3. The method of recovering zinc from matte containing sulphides of iron, copper and zinc which comprises digesting the matte with an aqueous solution of sulphuric acid in such an amount that there is produced a concentrated, substantially neutral solution of ferrous sulphate substantially free of all elements other than iron originally present in the matte, gaseous hydrogen sulphide containing sulphur originally combined with iron in the matte, and a solid residue conv taining all of the zinc and copper and a portion of the iron originally present in the matte, withdrawing the solution of ferrous sulphate, passing the residual solid material into contact with an aqueous solution of sulphuric acid in such amount that there is produced an acid solution containing the remaining iron of the matte as ferrous sulphate and a portion of the zinc of the matte as zinc sulphate, and a residue containing the remainder of the zinc as zinc sulphide and the copper as copper sulphide, withdrawing the acid solution and cooling it to crystallize zinc sulphate, employing the acid mother liquor as the aqueous sulphuric acid solution in the first mentioned digestion step, and treating the zinc sulphidecontaining residue to recover a zinc product therefrom.

4. The method of recovering zinc from sulphide bearing material containing gangue material and sulphi es of. iron a z c h h comprises sme ting the sulphide-bearing material under such conditions as to produce molten slag containing the gangue material and molten, acid-soluble matte containing the iron and zinc in sulphide forms, converting the matte to a solid, finely divided condition, digesting the matte with an aqueous solution of sulphuric acid in such an amount that there is produced a concentrated substantially saturated solution of ferrous sulphate saturated with respect to hydrogen sulphide and otherwise substantially free of all elements other than iron originally present in the matte, gaseous hydrogen sulphide containing sulphur originally combined with iron in the matte, and a solid residue containing all of the zinc and a portion of the iron originally present in the matte, withdrawing the solution of ferrous sulphate, passing the residual solid material into contact with an aqueous solution of sulphuric acid in such amount that there is produced an acid solution containing the remaining iron of the matte as ferrous sulphate and a portion of the zinc of the matte as zinc sulphate, and a residue containing the remainder of the zinc as zinc sulphide, withdrawing the acid solution and cooling it to crystallize zinc sulphate, employing the acid mother liquor as the aqueous sulphuric acid solution in the first mentioned digestion step, and treating the zinc sulphide-containing residue to recover a zinc product therefrom.

MARVIN J. UDY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 203,849 Parnell May 21, 1878 1,477,478 Elton et al. Dec. 11, 1923 1,937,636 Christensen Dec. 5, 1933 2,424,866 Udy July 29, 1947 OTHER REFERENCES Seidell, Solubilities of Inorganic and Organic Compounds, 2nd ed., 2nd printing, D. Van Nostrand, N. Y. (1919), vol. 1, pp. 343 and 754;, 

1. THE METHOD OF RECOVERING ZINC FROM MATTE CONTAINING SULPHIDES OF IRON AND ZINC WHICH COMPRISES DIGESTING THE MATTE IN FINELY DIVIDED FORM WITH AN AQUEOUS SOLUTION OF SULPHURIC ACID IN A COUNTER-CURRENT SYSTEM COMPRISING A SERIES OF RECEPTACLES, THE SULPHURIC ACID BEING OF SUCH CONCENTRATION AS TO PRODUCE A SUBSTANTIALLY NEUTRAL SOLUTION OF FERROUS SULPHATE WHEN REACTED WITH THE IRON SULPHIDE OF THE MATTER BY INTRODUCING UNTREATED MATTE INTO THE FIRST RECEPTACLE OF THE SERIES AND INTRODUCING THE SOLUTION OF SULPHURIC ACID INITALY INTO THE LEAST RECEPTACLE OF THE SERIES EFFECTING PARTIAL DECOMPOSITION OF THE MATTE AND PARTIAL CONSUMPTION OF THE ACID SOLUTION IN EACH RECEPTACLE, WITHDRAWING THE SUBSTANTIALLY NEUTRAL SOLUTION OF FERROUS SULPHATE FROM THE FIRST RECEPTACLE, CONTINUING THE DIGESTION TREATMENT BY PASSING RESIDUAL SOLID MATERIAL TO EACH OF THE VARIOUS RECEPTACLES IN SERIES FROM THE FIRST TO THE LAST AND PASSING THE ACID SOLUTION TO EACH OF THE RECEPTACLES IN SERIES FROM THE LAST TO THE FIRST, COOLING THE ACID SOLUTION AT A POINT INTERMEDIATE THE LAST AND FIRST RECEPTACLES TO CRYSTALLIZE AND RECOVER A PORTION OF THE ZINC OF THE MATTE AS ZINC SULPHATE, WITHDRAWING FROM THE LAST RECEPTACLE A SOLID OF THE MATTE IN THE FORM OF ZINC SULUOF THE ZINC OF THE MATTE IN THE FORM OF ZINC SULPHIDE AND TREATING THE SOLID RESIDUE TO RECOVER A ZINC PRODUCT THEREFROM. 